Comparing players across so many decades is always a stupid exercise. If you took any player from 40-50 years ago and brought them here to play in the NBA, they'd more than likely be completely and totally physically outmatched. It's no knock against the player, but the advances that have been made in nutrition, strength training, endurance training, etc. are huge. Now, if you took that person and they grew up today, it becomes a more apples to apples comparison.
Just as a little story about this. One of my friends was a strength training student at UConn and one of the professors in that program used to work with the Penn St. football team before he came over. He told the class that whenever Paterno was in the weight room (this is when he was essentially a figurehead and nothing else), everyone had to do one set to fail for whatever exercise they were doing, because that is what he believed was best. Anyone who has ever so much as played a HS sport in the last couple decades knows how incredibly ridiculous that is, so they'd pretend to work out until he left the room, at which point they'd go back to their real workouts.
So no, outside of maybe a handful of people, I don't think you'd find someone who could immediately jump 50 years into the future and be anywhere close to the player they were. I'd also just like to point out that the US population alone has nearly doubled in the past 50 years, to make no mention of the increase in international population and the spread of basketball, along with the SIGNIFICANT increase in earning potential as an NBA player to draw more potential players. The NBA players in decades past were the big fish in a MUCH, MUCH, MUCH smaller pool.